What Are Firefox Containers?
Firefox containers (officially “Multi-Account Containers”) are a built-in Firefox feature that
separates your browsing into color-coded tabs with independent cookies, sessions, and local storage. Each container
acts as a separate browsing identity within the same Firefox window.
This means you can log into the same website with different accounts simultaneously – one Gmail in your “Work”
container and another in your “Personal” container – without them interfering with each other. It’s Mozilla’s answer
to the multi-account browsing challenge.
How Firefox Containers Work
Technical Architecture
- Cookie isolation: Each container has its own cookie jar
- Storage separation: localStorage and indexedDB are independent per container
- Session independence: Login states don’t cross container boundaries
- Cache sharing: Page cache is shared (performance optimization)
- Same browser engine: All containers use the same Firefox rendering engine
What Containers Isolate
| Isolated (Separate) | Shared (Same) |
|---|---|
| Cookies | Browser fingerprint |
| localStorage | IP address |
| indexedDB | Extensions |
| Login sessions | Browser settings |
| Site data | Canvas fingerprint |
| Service workers | WebGL fingerprint |
| User agent | |
| Screen resolution |
Critical limitation: Firefox containers only isolate cookies and storage. They do NOT isolate
browser fingerprints, IP addresses, or hardware identifiers.
Setting Up Firefox Containers
Step 1: Install the Extension
- Open Firefox and go to
about:addons - Search for “Firefox Multi-Account Containers”
- Click “Add to Firefox” and confirm permissions
- The container icon appears in the toolbar
Note: Container support is built into Firefox, but the management extension makes it easy to use.
Step 2: Create Containers
- Click the Containers icon in the toolbar
- Select “Manage Containers”
- Click “+ New Container”
- Choose a name, color, and icon
- Click “OK” to create
Step 3: Organize Your Containers
Recommended container setup:
- 🔴 Personal: Personal email, social media, shopping
- 🔵 Work: Work email, company tools, professional platforms
- 🟢 Banking: Online banking and financial services
- 🟠 Shopping: E-commerce sites (prevents price tracking)
- 🟣 Social: Social media platforms
- 🟡 Research: General browsing and research
Step 4: Assign Sites
- Open a website in a container tab
- Click the Containers icon
- Toggle “Always Open in [Container Name]”
- The site will automatically open in that container going forward
Using Containers Effectively
Opening Container Tabs
- New container tab: Click Containers icon → select container
- Right-click link: “Open Link in New Container Tab”
- Long-press + button: Choose container for new tab
- Keyboard shortcut: Ctrl+Shift+1-8 (with extension config)
Visual Organization
Containers use color-coded tab indicators:
- Color bar at the top of each tab shows its container
- Container name displayed in the URL bar
- Icons help identify containers at a glance
- Consistent color scheme across sessions
Automatic Site Assignment
Set sites to always open in specific containers:
- Gmail → Work container
- Facebook → Social container
- Bank website → Banking container
- Amazon → Shopping container
Best Use Cases for Firefox Containers
Separating Work and Personal
The most common use case:
- Work email and tools in one container
- Personal email and social media in another
- No accidental login crossover
- Clear visual separation of contexts
Multiple Account Login
- Two Gmail accounts open simultaneously
- Development and production environments side by side
- Testing different user roles on the same site
- Client accounts for web developers
Privacy from Tracking
- Facebook cookies stay in the Social container
- Google tracking isolated to specific containers
- Shopping sites can’t follow you to other sites
- Reduces cross-site tracking effectiveness
Secure Banking
- Banking in a dedicated, clean container
- No tracking cookies from other sites
- Reduced risk of session hijacking
- Clear boundary around financial activities
Facebook Container Extension
Mozilla offers a specialized “Facebook Container” extension:
- Automatically isolates Facebook, Instagram, Messenger, and WhatsApp
- Prevents Facebook tracking pixels on other sites from linking to your profile
- External links from Facebook open outside the container
- Works alongside Multi-Account Containers
Limitations of Firefox Containers
No Fingerprint Isolation
The biggest limitation for multi-account users:
- Same browser fingerprint: All containers share identical canvas, WebGL, and audio fingerprints
- Same user agent: Platform detection identical across containers
- Same screen properties: Resolution, color depth shared
- Same font list: Installed fonts identical across containers
Consequence: Platforms that use fingerprinting (Facebook, Amazon, eBay, Google) can link accounts
across containers. This makes Firefox containers unsuitable for managing multiple accounts on platforms that
employ fingerprinting.
Same IP Address
- All containers share your real IP address
- No per-container proxy support
- Platforms see all accounts coming from the same IP
- Geographic location identical for all containers
Extension Sharing
- All containers share the same extensions
- Extension data may leak between containers
- Some extensions don’t respect container boundaries
Limited Customization
- Cannot set different timezone per container
- Cannot configure different languages
- Cannot modify user agent per container
- Cannot control WebRTC behavior per container
Firefox Containers vs. Antidetect Browsers
| Feature | Firefox Containers | Send.win (Antidetect) |
|---|---|---|
| Cookie Isolation | ✅ Yes | ✅ Yes |
| Fingerprint Isolation | ❌ No (shared) | ✅ Yes (unique per profile) |
| IP Isolation | ❌ No (shared) | ✅ Yes (proxy per profile) |
| Multi-Account Safe | ⚠️ Basic sites only | ✅ All platforms |
| Price | ✅ Free | Subscription |
| Ease of Use | ✅ Very easy | ✅ Easy |
| Team Sharing | ❌ No | ✅ Yes |
| Cross-Device | ❌ Desktop only | ✅ Any device |
Use Firefox Containers when:
- Separating work/personal browsing
- Basic multi-login (low-risk sites)
- Privacy from cross-site tracking cookies
- Free solution is sufficient
How Send.win Helps You Master Firefox Containers
Send.win makes Firefox Containers simple and secure with powerful browser isolation technology:
- Browser Isolation – Every tab runs in a sandboxed environment
- Cloud Sync – Access your sessions from any device
- Multi-Account Management – Manage unlimited accounts safely
- No Installation Required – Works instantly in your browser
- Affordable Pricing – Enterprise features without enterprise costs
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Experience the power of browser isolation with our free demo:
- Instant Access – Start testing in seconds
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- Secure – Bank-level encryption
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Use Send.win when:
- Managing accounts on platforms with fingerprinting
- Need unique IP per account
- Team needs to share account access
- Accounts must appear on different devices
Advanced Container Tips
Temporary Containers Extension
- Auto-creates a new container for every new tab
- Container deleted when tab closes
- No persistent tracking between tabs
- Like permanent incognito but with container features
Container Proxy (Third-Party)
- Some extensions add per-container proxy support
- “Container Proxy” extension routes traffic differently per container
- Adds IP isolation to container functionality
- Still doesn’t address fingerprint sharing
Keyboard Shortcuts
- Configure shortcuts for quick container switching
- Set default container for new tabs
- Use “Always open in” rules for common sites
Privacy Comparison
| Privacy Feature | Regular Tabs | Incognito | Containers | Antidetect |
|---|---|---|---|---|
| Cookie Isolation | ❌ | ✅ (temp) | ✅ (persistent) | ✅ |
| Fingerprint Isolation | ❌ | ❌ | ❌ | ✅ |
| IP Isolation | ❌ | ❌ | ❌ | ✅ |
| Session Persistence | ✅ | ❌ | ✅ | ✅ |
| Multi-Login | ❌ | ⚠️ (one extra) | ✅ | ✅ |
Frequently Asked Questions
Are Firefox containers built into Firefox?
Yes, the underlying container technology is built into Firefox. The “Multi-Account Containers” extension provides the
user interface for managing containers. You can also use containers via about:config without the
extension.
Can websites detect I’m using containers?
Websites cannot directly detect container usage. However, they can fingerprint your browser and see that multiple
accounts share the same fingerprint, which is as identifying as not using containers at all for platforms that
fingerprint.
Do containers work with Firefox Sync?
Container configurations are not synced through Firefox Sync by default. Your container tabs and site assignments
stay on the local device.
Can I export container data?
The extension allows exporting container configurations as JSON. However, cookies and session data within containers
cannot be easily exported or transferred.
How many containers can I create?
There’s no hard limit. You can create as many containers as you need. However, managing more than 10-15 containers
becomes unwieldy without strong organizational habits.
Conclusion
Firefox containers are an excellent free tool for separating browsing contexts and preventing
cross-site cookie tracking. They’re perfect for everyday use cases like separating work and personal browsing or
logging into multiple accounts on basic websites.
However, containers have a fundamental limitation: they don’t isolate browser fingerprints or IP addresses. For
platforms that use fingerprinting to detect multi-account usage (which includes most major platforms in 2026),
containers alone aren’t sufficient.
For serious multi-account management, Send.win provides what containers cannot: unique browser
fingerprints, per-profile IP addresses, team collaboration, and cross-device access. Use Firefox containers for
daily convenience and antidetect browsers for professional account management.